Most computer monitors have "landscape" resolutions, i.e., the view width is more than the view height in pixels. Some special units are made to present a "portrait" view. This is often desirable for systems that process long documents, but the (native) portrait monitors are usually much more expensive.

The data sent to a monitor can be converted from the "normal" landscape format to the portrait format, which will allow the cheaper landscape monitor to be physically rotated ninety degrees. The software conversion from landscape to portrait is typically rather slow, since it is compute intensive.

Some graphics GPUs have hardware that can be used for hardware acceleration of the data conversion, allowing the cheaper monitors to be used in systems without much loss in performance.

Without hardware accelertion, rotation of the cheaper monitor can result in significant performance penalities.

Hardware-accelerated Rotation
There are several Summit Series products that offer the Rotation feature. All use hardware acceleration.

Desktop systems with a couple of 1920x1200 monitors rotated to portrait and configured as a single desktop provides a reasonably large amount of real estate for "desktop publishing" tasks. Such configurations are very economical and very fast when used with Accelerated-X.